An electronic commutation motor (referred to as “EC-motor” herein) is a high efficiency electrical machine that operates with pulse modulation at, for example, ultrasonic frequencies. One example of an EC-motor is disclosed in U.S. Pat. No. 6,163,122 to De Filippis. Although not limited to use in the circuitry for motor vehicles, EC-motors are commonly used in motor vehicle construction as disclosed in U.S. Pat. No. 6,107,696 to Peter et al. and U.S. Pat. No. 6,502,652 to Rogg such as to provide power to operate a compressor of an air-conditioning system, or such as to provide an electromechanical energy converter arranged in the drive train, etc.
Known motor controls, such as are used to control EC-motors, compare a set value with an actual value obtained from a potentiometer for determining the position of a control unit. A controller present in the motor control produces a signal that is conducted to a four-quadrant amplifier. By the assistance of this signal, the electric motor is driven with such a current, that it effects the angular position predetermined by the set value.
Departing from this state of the art, German Document DE 3935593 A1, for example, proposes a device that can leave out a potentiometer for determining the position signal. In other words, this device does not include a potentiometer for determining the position signal. The determination of the position of the control member (control unit) results from, in one embodiment, the measurement and analysis of partial movements of a DC motor for moving the control unit. In this case, for progress of each armature segment of the DC motor, impulse recognition of the motor current is carried out, wherein an impulse is released and led to a controller. In a further embodiment, a Hall transmitter, or, as the case may be, a light detection device is employed instead of an impulse recognition device.
With the use of an electronic commutation motor (EC-motor), the correct current of individual motor windings is effected by means of the evaluation of the rotor position sensor of the EC-motor and production of a corresponding commutation impulse. Comprehensive embodiments of this feature are also disclosed in German Document DE 10065488 A1.
EC-motors are evermore preferred because of their better reliability, but their use is kept minimal, because EC-motors have the disadvantage that they require rotor position indication for commutation and commutation electronics. These components make EC-motors expensive.
A further measurement device for reporting the position of a control unit is described in German Document DE 19915988 A1. In this case, a Hall sensor is used as a position indicator, wherein the Hall sensor is programmable, and whereby temperature dependent measurement errors can be corrected. No statements are made with respect to the “position control”/“position determination” of the motor, or, as the case may be, the motor control for positioning of the control unit.
It is an object of the present invention to present a simple motor control for a EC-motor for controlling a control unit.